The invention is concerned with an improvement for a feed regulator for a sewing machine; more particularly, with a device to restrict the movement of a feed regulator while the transport of a work material is being effected.
In the prior art there are many examples of sewing machines having feed systems utilizing one or another form of feed regulator to permit adjustment of stitch length. In the bulk of these prior art feed systems it has been noted that an undue loading of the feed system, for example, by stitching on a heavy work material or by applying tension to the work material, can result in temporary or permanent repositioning of the feed regulator by the feedback of forces to the regulator through the feeding dogs.
In those machines where the position of the feed regulator is controlled by means of a manually variable cam and/or by a work patterning cam, the feed back of forces through the feeding dog can be controlled by means of a spring acting on the feed regulator in a fashion to press the cam followers against the cams. Thus the feedback forces are compensated for to the extent of the force exerted by the spring. Problems have been encountered in those sewing machines having provisions for quick reverse through a depressible control in that a spring force which may be appreciable must be overcome; and in those sewing machines having a work patterning cam in that a cam material is required which is sufficient to withstand the spring force.
What is required is a feed system which is not effected by feedback of forces through the feeding dog, without the necessity for spring bias forces, and the adverse results thereof, heretofore required.